Though your car is a W126 vs. my W116, there should be some similarities. For the front I would place the jackstands where that cross brace is welded to the car. If it's like mine, it's basicly a large tube that stretches across the car. For the back, I would use the point where the trailing A arm bolts up. Not the trailing A arm itself but, where it bolts to the floor pan. What ever you do, DO NOT places jackstands on the rear axle half shafts. You can't really place a jackstand on the rear differential itself without the car tipping one direction or the other. This would not be a good thing.
1994 MB E320 Coupe (199,500 mi)
1992 MB 190E 2.6 (173,000 mi)
1983 Porsche 911SC (148,000 mi)
2004 Volvo V70 2.5T (198,000 mi)
President of CT/Westchester Section